1. Field of the Invention
The present invention relates to an attachment structure of a seat belt system for a rear seat, and particularly to an attachment structure of a three-point seat belt system for a center seat of a three occupant rear seat in a vehicle such as a station wagon.
2. Description of the Related Art
In recent years, in a vehicle, for the purpose of improving the safety of a passenger, there is a tendency to adopt a three-point seat belt system for a rear seat as well.
In a station wagon in which a rear seat is made of a three occupant seat, at both the right and left seat portions of the rear seat, the structure of a seat belt system can be easily made a three-point type by fixing a seat belt retractor to a C-pillar. However, at the center seat portion of the rear seat, a two-point seat belt system has been generally adopted, because it is difficult to secure a fixing place for a seat belt retractor.
In a rear seat of such a station wagon, for the purpose of providing a three-point seat belt system at the center seat as well, for example, as disclosed in Japanese Patent Unexamined Publication No. Sho. 63-130448, it is conceivable that a seat belt retractor for the center seat portion is provided at the lower surface of the roof center portion in the vehicle compartment.
However, in order to provide the seat belt retractor at the lower surface of the roof center portion in the vehicle compartment as set forth above, it is necessary to reinforce the roof, which causes an increase in vehicle weight and an increase in manufacturing cost.
In addition, there has been hitherto proposed a technique for making a seat belt system for the center seat portion a three-point type by reinforcing the back of the rear seat and its peripheral member, and by fixing a seat belt retractor to the inside of the thus reinforced back of the rear seat. However, reinforcing the back of the rear seat and its peripheral member causes an increase in vehicle weight and an increase in manufacturing cost similarly to the foregoing technique.
On the other hand, when a seat belt retractor is fixed to a floor of a luggage room behind the rear seat to make a seat belt system of the center of the rear seat a three-point type, it not only becomes difficult to draw out a belt when using the seat belt, but also there is a fear that the usefulness of the luggage room will be deteriorated while the seat belt system is used.